Count number of Users

Question

I have a Client class, and a Systems Class.

A customer has one or more systems:

public class ClienteEmpresa : Pessoa
{

 public virtual ICollection<TipoDeSistemas> TipoDeSistemas { get; set; }
}

And the systems class has one or many Clients:

 public class TipoDeSistemas
    { 
  public virtual ICollection<ClienteEmpresa> ClienteEmpresa { get; set; }
    }

I’d like to know how I count how many users use the X system. for example: Maria, João, José, and Lurdes, use the system W. wanted to know how to do this Count(), using Entity, with labdas expressions. Someone to give me a hint?

I made a way here, that’s worked.

List<TipoDeSistemas> sis = db.TipoDeSistemaDb.ToList();

            var si = sis.Find(c => c.Descricao == "SMC");
            ViewBag.Smc = si.ClienteEmpresa.Count(c => c.StatusCliente == StatusCliente.Ativo);

            var merchant = sis.Find(c => c.Descricao == "MERCHANT");
            ViewBag.Merchantd = merchant.ClienteEmpresa.Count(c => c.StatusCliente == StatusCliente.Ativo);

            var manifestacao = sis.Find(c => c.Descricao == "MANIFESTAÇÃO");
            ViewBag.Manifestacao = manifestacao.ClienteEmpresa.Count(c => c.StatusCliente == StatusCliente.Ativo);

            var cte = sis.Find(c => c.Descricao == "CT-e");
            ViewBag.CTe = cte.ClienteEmpresa.Count(c => c.StatusCliente == StatusCliente.Ativo);